1. Field of the Invention
The present invention relates to a recording material suitable for inkjet recording using liquid ink such as water-based inks (a dye or a pigment is used as a coloring material), oil-based inks, or the like and solid inks which is a solid at a room temperature but are melted and liquefied for printing. The invention also relates to a fine particle dispersion to be used for the production of the recording material; and a method for producing the dispersion. More particularly, the invention relates to an ink-jet recording sheet which is highly glossy and having high printing density; a fine particle dispersion used for the production, and its production method. The invention also relates to a coating solution for coloring agent accepting layer for ink-jet recording sheet using the fine particle dispersion.
2. Description of the Related Art
In recent years, with the rapid advance of the information technology industries, various information processing systems have been developed. Recording methods and devices suitable for the latest information systems have also been developed and put into practical use.
Among these recording methods, an ink-jet recording method has been used widely for not only offices but also so-called home use. The advantages of the method is that the method can be applied to a variety of recording materials, the hardware (apparatus) is relatively economical, compact and quiet.
Further, along with recent advancements in resolution of ink-jet printers, it has been enabled to obtain so-called photo-like recorded matter with high image quality. Following such progress of the hardware (apparatuses), various types of ink-jet recording sheets have been developed.
The desired traits of the ink-jet recording sheets generally include (1) rapid drying (a high ink absorption rate); (2) a correct and uniform diameter of ink dots (no blurring); (3) an excellent graininess; (4) a high circularity of dots; (5) a high color density; (6) a high saturation (without dullness); (7) excellent water resistance, light resistance, and ozone resistance ;(8) high whiteness of recording sheets; (9) excellent shelf stability of the recording sheets [i.e., yellowing or blurring does not occur during long-term storage ]; (10) resistance to deformation and good dimensional stability (sufficiently low curling); and (11) good hardware running.
Further, in order to obtain photograph-like high-quality prints, the photo glossy paper should possess traits such as good glossiness, surface smoothness and the photographic paper-like feel similar to that of silver salt photographs and the like.
For the purpose of improving the above-mentioned various characteristics, ink-jet recording in which coloring agent accepting layer has a porous structure have been developed and put to practical use in recent years. Such ink-jet recording sheets are excellent in ink accepting property (a rapid drying property) and highly glossy.
For example, in Japanese Patent Application Laid-Open (JP-A) Nos. 10-119423 and 10-217601, ink-jet recording sheets comprising an highly porous coloring agent accepting layer formed on a support, which accepting layer contains minute inorganic pigment particles and a water-soluble resin, are proposed.
These recording sheets, particularly ink-jet recording sheets having the coloring agent accepting layer which is composed of a porous structure and which contains silica as the fine particle of inorganic pigment, are considered to be excellent in ink absorbency and to have so high ink accepting capacity to form images with high resolution and high glossiness due to such composition.
However, the color density and glossy feel of the ink-jet recording sheet are yet insufficient compared to those of silver salt photograph.
Ordinally, ink-jet recording sheets are produced by applying a coating solution for a coloring agent accepting layer, to a support. The coating solution for a coloring agent accepting layer is produced by, pre-dispersing an aqueous solution containing fine particles and a cationic polymer, then further granulating the fine particles to obtain an particle dispersion, and adding a water-soluble resin to the dispersion. A cross-linking agent and the like can be optionally added to the dispersion. However, a coating solution for the coloring agent accepting layer produced in such a manner often becomes highly viscous and loses suitability to coating and suitability to filtration.